Preparation, structure, and thermochemical properties of a copper(II) Schiff-base complex

A copper(II) Schiff-base complex [CuL·2MeOH·H2O] was prepared by reaction of the ligand [H2L = N, N′-o-phenylene-bis(3-methoxysalicylideneimine)] and Cu(OAc)2·H2O in methanol at 328.15 K. X-ray diffraction analysis revealed that the title complex was crystallized in the triclinic crystal system with space group P–1, in which copper(II) ion was located in the N2O2 ligand binding sites. According to two designed thermochemical cycles, the dissolution enthalpies of relevant substances of two reactions in the calorimetric solvents were determined by a solution-reaction isoperibol calorimeter, respectively. Combined with some other auxiliary thermodynamic data, the standard molar enthalpies of formation of the ligand and the complex were calculated to be: \( \Delta_{\text{f}} H_{\text{m}}^{\theta } \)[H2L(s), 298.15 K] = −(384.2 ± 9.10) kJ mol−1 and \( \Delta_{\text{f}} H_{\text{m}}^{\theta } \)[CuL·2MeOH·H2O (s), 298.15 K] = −(1072.6 ± 9.2) kJ mol−1.